1. Field of the Invention
The present invention generally relates to a fuel supply control device for an engine. More specifically, the present invention relates to an engine fuel supply control device that stops the supply of fuel (performs fuel cut-off) after a specific delay time has elapsed since a specific fuel cut-off condition was met.
2. Background Information
Fuel cut-off in which the supply of fuel is stopped when a specific fuel cut-off condition has been met, such as whether the accelerator pedal has fully returned, has been performed in the past in order to prevent the air-fuel mixture from being too rich during deceleration and to reduce fuel consumption. One commonly known method of a fuel cut-off using a cut-in delay is disclosed in Japanese Patent No. 2,605,755 (p. 3, column block, lines 6-15). In this method, after a specific fuel cut-off condition has been met, the supply of fuel is not stopped right away, but is instead stopped after a specific delay time has elapsed. This delay time is changed according to whether the transmission range is in a neutral range or a drive range. If the supply of fuel is stopped suddenly because the accelerator pedal has fully returned and the throttle valve has completely closed, engine torque drops off sharply and jerks the driver forward too harshly. However, with a cut-in delay, engine torque is gradually reduced as the amount of air remaining in the intake passage downstream from the throttle valve decreases, and the supply of fuel is stopped at the point when engine torque has been sufficiently reduced, so the jerking sensation is lessened. In particular, with this design, when the transmission is in the neutral range, the delay time is set shorter so that the air/fuel ratio will not be transiently rich, which prevents emission problems, but when the transmission is in the drive range, the delay time is set longer so that torque (engine speed) can be reduced smoothly, which prevents deceleration shock and noise produced by the drive train.
With the aim of higher engine output and efficiency, the volume of collectors has been on the rise in recent years. In order to effectively minimize the jerking sensation during deceleration with an engine such as this, an increase in collector volume has been accompanied by the need to set the cut-in delay time longer than in the past.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved engine fuel supply control device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.